1. Field of the Invention
The present invention relates generally to a structure for eliminating bright lines occurred at joints between small-size light guide plates (LGP) which constitute a large-size tiled LGP, wherein the bright lines are usually caused by refraction of light at the joints due to the medium variation.
2. The Prior Arts
Liquid crystal display (LCD) panels are widely used in many electronic products, such as notebook computers, computer displays, mobile phones, or LCD televisions. Typically, the operation of an LCD panel must be facilitated with a backlight module for providing a backlight to illuminate the LCD panel for displaying images. As such, the backlight module is a necessary part of the LCD panel. Further, backlight modules may even employed in other electronic products which require for backlight illumination.
A typical backlight module employed in an LCD panel usually includes a LGP and a backlight source. Most conventional LCD televisions adopt lamps serving as backlight sources installed at back sides of the LGPs. However, this disadvantageously increases the overall thickness of the LCD televisions. In order to produce LCD televisions having a smaller thickness, it has been proposed to employ light emitting diodes (LED) serving as a backlight source of the backlight module. In such a backlight module, a plurality of LEDs are provided at a side edge of the LGP, a reflective sheet is provided at a first surface of the LGP, and a plurality of optical sheets including a diffusion sheet and a prism sheet are provided at a second surface of the LGP opposite to the first surface. All of these elements are then framed in an outer frame. The backlight source emits a light. The light is then projected into the LGP from the side edge of the LGP. A part of the light is then reflected, and then sequentially passes through the diffusion sheet and the prism sheet for outputting.
The LGP is an optical apparatus, and is usually required for a high caliber of optical precision and performance. As such, a large-size LGP is usually harder for fabrication and requires a higher cost than a small-size LGP. Accordingly, it is further proposed to tile a plurality of small-size LGPs into a large-size LGP for a large-size LCD display.
Referring to FIG. 8, there is shown a tiled LGP structure including a plurality of flat small-size LGPs 1. Each of the flat small-size LGPs 1 has at least one jointing side 12, and a lateral side. Prior to fabricating the tiled LGP structure, the jointing sides 12 of the flat small-size LGPs 1 are polished, so as to allow the jointing sides 12 of each two neighboring small-size LGPs 1 to be closely contacted and form a joint therebetween. Each of the small-size LGPs 1 is provided with one or more LED backlight sources 2 at the lateral side thereof. The LED backlight sources 2 are adapted for projecting a light into the tiled LGP structure. The light is then transmitted inside the tiled LGP structure, and then achieves a performance as a surface light source. However, the joint between the jointing sides 12 of the small-size LGPs 1 present a different medium feature relative to the small-size LGPs 1. As such, the light is likely to be refracted at the joint between the jointing sides 12 of the small-size LGPs 1, thus producing a bright line C having a brightness higher than an average brightness of the tiled LGP structure (as indicated in the brightness curve shown in FIG. 8A).